transformer-lens-interpretability

Analyze and steer transformer activations with TransformerLens for mechanistic interpretability.

1.0k|117|Updated Feb 26, 2026
One-click install
npx skills add https://github.com/OpenLAIR/dr-claw --skill transformer-lens-interpretability-openlair
Or copy as Structured Prompt for Agent
Please help me install this Agent Skill.
Skill: transformer-lens-interpretability
Source: https://github.com/OpenLAIR/dr-claw/tree/main/skills/mechanistic-interpretability/transformer-lens
Command: npx skills add https://github.com/OpenLAIR/dr-claw --skill transformer-lens-interpretability-openlair

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve?

TransformerLens provides a structured approach to probing transformer internals, enabling researchers to inspect activations, patch activations, and trace causal contributions to predictions.

Core Features & Use Cases

  • Activation caching and inspection of resid_post, pattern, and z activations
  • HookedTransformer and HookPoints for safe, controlled activation manipulation
  • Activation patching and causal tracing to quantify influence on outputs
  • Induction head and IOI circuit analysis to reveal circuit-level behavior
  • Logit attribution and visualization to understand contribution pathways
  • Ecosystem integration with related tooling and tutorials for guided workflows

Quick Start

Install transformer-lens, load a pretrained GPT-2 with HookedTransformer, run run_with_cache on an input to inspect activations, then apply a forward hook to patch activations and observe the impact on the output.

Frequently Asked Questions about transformer-lens-interpretability

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I perform activation patching on a GPT-style model to trace causal contributions?

You can discover IOI circuits by using HookPoints for controlled activation manipulation, running run_with_cache to inspect pattern and z activations, then applying activation patching to quantify how specific components influence the indirect object identification behavior.

What is mechanistic interpretability and how does TransformerLens expose transformer internals?

Mechanistic interpretability analyzes transformer behavior by inspecting and manipulating internal activations. TransformerLens exposes resid_post, pattern, and z activations through caching and hook utilities, allowing researchers to trace causal contributions to predictions across GPT-style models.

Can I inspect attention patterns and logit attribution across different pretrained transformer checkpoints?

Yes, you can inspect attention patterns and logit attribution by loading compatible pretrained model checkpoints into HookedTransformer, running run_with_cache to extract pattern activations, and visualizing the contribution pathways to understand prediction behavior.

How do I set up the environment for mechanistic interpretability experiments with transformer-lens?

Mechanistic interpretability experiments require installing the transformer-lens package and obtaining compatible GPT-style model checkpoints. You then load the model as a HookedTransformer and use run_with_hooks and run_with_cache utilities to execute patching and caching workflows.

What is the best way to analyze induction heads in transformer models?

Analyzing induction heads involves loading a pretrained model with HookedTransformer, using run_with_cache to extract and inspect attention pattern activations, and applying logit attribution to reveal the circuit-level behavior driving the induction mechanism.

When should I not use activation patching for interpreting transformer behavior?

Activation patching has limitations when used without compatible model checkpoints or the transformer-lens package. It is not suitable for non-GPT-style architectures, and researchers should avoid drawing conclusions without properly caching baseline activations for causal comparison.